XML - 未按所需顺序输出的元素

I want to change the order that the elements are outputted in. It currently displays them like this: "Maths:English:Science:ABA (GCSE);(GCSE);(GCSE);" I need a way of ordering it so that I can display it like this: "Maths:A (GCSE); English:B (GCSE); Science:A (GCSE);" I am a novice with XML so please try not to show any overcomplicated solutions if possible!I want to change the order that the elements ar